"If you know that your new wonderfully effective pain medication increases the risk of heart attacks from 4% to 6% (or whatever the numbers were), are you going to disclose that to the FDA, knowing it essentially spells doom for the billion dollars plus you spent on development?"

Did Merck not disclose something? http://en.wikipedia.org/wiki/Vioxx seems to indicate they did disclose the increased risk over naproxen, but tried to explain it away without further investigation.